JP7011051B2 - Methods and equipment to identify valid or invalid channels - Google Patents

Description

The present disclosure relates to methods and devices for identifying valid or invalid channels.

In Patent Document 1, in order to reduce the porosity of the porous body and increase the permeability of the porous body, fluid analysis is performed based on the pseudoporous body data, and the flow velocity for each space voxel is obtained. Disclose that we derive information about. Patent Document 1 discloses that a spatial voxel having a low flow velocity is preferentially replaced with an object voxel, whereby the porosity is set to a target value.

Patent Document 2 discloses that the pore diameter of a wall flow type exhaust gas purification filter is observed based on an SEM image (see FIG. 4 of Patent Document 2).

Japanese Unexamined Patent Publication No. 2015-189666 Japanese Unexamined Patent Publication No. 2013-53589

The inventors of the present application have newly found the significance of being able to more accurately evaluate the performance of a porous body by distinguishing between an effective flow path in which a fluid flows from an inflow surface to an outflow surface and another flow path. ..

In the method according to one aspect of the present disclosure, fluid analysis is performed on the porous body based on structural data showing a three-dimensional structure of the porous body that should have an inflow surface and an outflow surface, and at least in a flow path contained in the porous body. The process of generating data showing the pressure distribution of the fluid and
A step of specifying an effective flow path for flowing the fluid from the inflow surface to the outflow surface based on a gradient of a pressure value generated along the flow direction of the fluid in the flow path is included.

In some cases, the effective flow path is identified based on a plurality of isobaric surfaces having different pressure values along the flow direction of the fluid in the flow path.

In some cases, the cross-sectional area of the effective flow path is determined based on the isobaric surface.

In some cases, the volume of the effective flow path is determined based on the isobaric surface.

In some cases, the partial volume of the effective flow path is at least based on the distance between the first isobaric surface and the second isobaric surface in the flow direction of the fluid and the area of the first and / or second isobaric surface. Will be decided.

In some cases, the method determines the ratio of the total value of the individual cross-sectional areas of the effective flow path in the cross section of the porous body to the total value of the individual cross-sectional areas of the pores contained in the cross section of the porous body. Further includes steps to be performed.

In some cases, the method further comprises the step of determining the ratio of the volume of the effective flow path to the total volume of pores contained in the porous body.

In some cases, the method is the ratio of the total cross-sectional area of the effective flow path contained in the cross section of the porous body to the total cross-sectional area of both the pores and the ceramics portion in a cross section of the porous body. Further includes a step of determining.

In some cases, the method further comprises the step of determining the ratio of the volume of the effective flow path to the volume of the porous body.

In some cases, the method further comprises determining the equivalent diameter of the isobaric surface based on the area and perimeter of the isobaric surface.

In some cases, the method further comprises the step of determining the equivalent diameter distribution.

In some cases, the method further comprises determining the distribution of the number of said isobaric surfaces of equivalent diameter within the same or the same range.

In some cases, the data also show the flow velocity distribution of the fluid flowing through the flow path.
The flow rate of the fluid passing through the isobaric surface in a unit time is determined based on the area of the isobaric surface in which equal pressure values are distributed in the effective flow path intersecting the flow direction of the fluid and the flow velocity indicated by the data. Further includes steps.

In some cases, the method further comprises determining the flow rate flowing through some or all of the effective flow rates contained in the porous body based on the sum of the flow rates determined for each isobaric surface.

In some cases, the method further comprises determining an evaluation value for filter characteristics for the isobaric surface based on the flow rate determined for the isobaric surface.

In some cases, the structural data is a three-dimensional set of voxels with digital values.

In some cases, the method further comprises the step of setting grid points for the structural data.
The separation distance of isobaric surfaces having different pressure values along the flow direction of the fluid in the flow path includes a separation distance that is less than the grid spacing in the structural data.

The apparatus according to one aspect of the present disclosure performs fluid analysis on the porous body based on structural data showing a three-dimensional structure of the porous body that should have an inflow surface and an outflow surface, and at least in a flow path included in the porous body. Generates data showing the pressure distribution of the fluid
It is configured to identify an effective flow path for flowing the fluid from the inflow surface to the outflow surface based on the gradient of the pressure value generated along the flow direction of the fluid in the flow path.

In the method according to one aspect of the present disclosure, fluid analysis is performed on the porous body based on structural data showing a three-dimensional structure of the porous body that should have an inflow surface and an outflow surface, and at least in a flow path contained in the porous body. The process of generating data showing the pressure distribution of the fluid and
It comprises a step of identifying an ineffective flow path that does not allow the fluid to flow from the inflow surface to the outflow surface based on a set of pressure values within a predetermined range that does not indicate the flow of the fluid in the flow path.

The apparatus according to one aspect of the present disclosure performs fluid analysis on the porous body based on structural data showing a three-dimensional structure of the porous body that should have an inflow surface and an outflow surface, and at least in a flow path included in the porous body. Generates data showing the pressure distribution of the fluid
Based on a set of pressure values within a predetermined range that does not indicate the flow of the fluid in the flow path, it is configured to identify an ineffective flow path that does not allow the fluid to flow from the inflow surface to the outflow surface.

According to one aspect of the present disclosure, it is possible to specify an effective flow path in which a fluid flows from an inflow surface to an outflow surface and / or an ineffective flow path in which a fluid does not flow from an inflow surface to an outflow surface.

It is a schematic perspective view of the ceramics filter which concerns on one aspect of this disclosure. It is a schematic perspective view of the segment included in the ceramics filter which concerns on one aspect of this disclosure. It is a schematic diagram which shows the schematic cross section of the segment in the plane PL3 of FIG. The opening cells are complementarily sealed by a plurality of sealing portions at the first end and the second end of the honeycomb structure having the opening cells defined by the porous partition wall. Fluid can move between adjacent open cells via the porous septum that defines the open cells. It is a schematic block diagram of the system for carrying out the method of this disclosure. It is a schematic perspective view of the porous body shown by the structural data acquired by the X-ray CT apparatus. It is a schematic diagram which shows the schematic partial cross section of the porous body shown in FIG. 5, and the part surrounded by a solid line shows a pore. It is a schematic diagram which shows the result of the fluid analysis performed about the simplified flow path. It is a graph which shows the change of the pressure value in the isobaric surface shown in FIG. 7. It is a schematic schematic diagram which mainly shows the flow path contained in a porous body. It is a reference figure which shows typically the boundary of the effective flow path and the invalid flow path in the cross section VV of FIG. It is a schematic diagram which shows the schematic partial cross section of the porous body shown in FIG. 5, the solid line shows the pore which is a partial space of an effective flow path, and the dotted line shows the pore which is a partial space of an invalid flow path. It is a schematic flowchart about the method of specifying the effective flow path of this disclosure. It is a schematic flowchart regarding the method of identifying an invalid flow path of this disclosure. It is a graph which shows the ratio of a ceramic part, an effective pore, and an ineffective pore. It is a schematic diagram which shows the case where the difference ΔP of the pressure value which determines the interval of the isobaric surface is small.

Hereinafter, non-limiting embodiments of the present invention will be described with reference to FIGS. 1 to 15. One of ordinary skill in the art can combine the individual features contained in each embodiment and / or each embodiment without over-explanation. Those skilled in the art can also understand the synergistic effect of this combination. Overlapping description between embodiments will be omitted in principle. The reference drawings are primarily intended to describe the invention and may be simplified for convenience of drawing. The individual features specified by the expression "in some cases" are not only valid for, for example, the methods and / or devices of the present disclosure, but are universally applicable to various other methods and / or devices. It is understood as a characteristic feature.

The ceramic filter 90 shown in FIG. 1 is a functional component that filters a fluid such as a gas, a liquid, a powder, or a mixture thereof. The fluid flowing through the ceramic filter 90 is typically exhaust gas exhausted from the engine. The ceramic filter 90 is not necessarily limited to this, but is used for purifying exhaust gas exhausted from an engine such as a gasoline engine and a diesel engine. Specifically, the ceramic filter 90 collects particulate matter (PM) in the exhaust gas. The collected particulate matter is burned and removed in the ceramic filter 90.

The ceramic filter 90 is a cylinder having an inflow surface 91 and an outflow surface 92 on the opposite side of the inflow surface 91. The ceramic filter 90 is not necessarily limited to a cylindrical body, and can take other shapes. The ceramic filter 90 is constructed from a plurality of segments 80, but is not limited to this. It is also assumed that the ceramic filter 90 is a monolithic body. In the case where the ceramic filter 90 is constructed from a plurality of segments 80 without any limitation, the number of segments 80 increases or decreases depending on the size of the ceramic filter 90. A ceramic intermediate layer 93 is formed between the segments 80, which promotes the integration of the segments 80. The method for constructing the ceramic filter 90 from the segment 80 is well known in the present technical field, and detailed description thereof will be omitted.

When the ceramic filter 90 is constructed from a plurality of segments 80, the segment 80 is a prism having an inflow surface 81 and an outflow surface 82, as shown in FIGS. 2 and 3. The segment 80 is not necessarily limited to a prism, and can take other shapes. The segment 80 has a porous partition wall 86 that defines the opening cell 85 through which the fluid flows, and a sealing portion 87 that is provided so that the fluid flows between the adjacent opening cells 85 via the porous partition wall 86. As can be clearly seen from FIG. 3, the arrangement pattern of the sealing portion 87 on the inflow surface 81 side of the segment 80 and the arrangement pattern of the sealing portion 87 on the outflow surface 82 side of the segment 80 are complementary. In other words, the opening cell 85 whose opening end on the inflow surface 81 side is not sealed by the sealing portion 87 has an opening end on the outflow surface 82 side sealed by the sealing portion 87. The opening cell 85 whose opening end on the inflow surface 81 side is sealed by the sealing portion 87 has an opening end on the outflow surface 82 side which is not sealed by the sealing portion 87. The arrangement of the sealing portion 87 causes the fluid to move through the porous partition wall 86 as schematically shown in FIG. From the viewpoint that the fluid moves through the porous partition wall 86 in this way, the ceramic filter 90 or the segment 80 is called a wall flow type.

The ceramic filter 90 or the segment 80 that may be contained therein is made of a ceramic material such as silicon carbide (SiC), cordierite (2MgO · 2Al _{2O 3.5SiO 2), aluminum silicate (Al 2 TiO 5 ) .} The bond of silicon carbide (SiC) can be a Si bond, a SiC bond, a cordierite bond, or the like. The opening shape of the opening cell 85 is not limited to a rectangular shape, but may be another polygonal shape such as a hexagonal shape. The thickness of the partition wall 86 and the cell density of the opening cell 85 are appropriately set according to the application and the required performance. The method for manufacturing the segment 80 is well known in the art, and detailed description thereof will be omitted.

The fluid flows between adjacent opening cells 85 via the porous partition wall 86 (specifically, a portion thereof) described above. Specifically, as shown in FIG. 3, the exhaust gas flowing into the opening cell 85k flows into the opening cell 85j via the porous partition wall 86h. The porous partition wall 86h has an inflow surface 861 and an outflow surface 862 on the opposite side of the inflow surface 861. The porous partition wall 86 includes an effective flow path for flowing exhaust gas from the inflow surface 861 to the outflow surface 862. The exhaust gas that has flowed into the partition wall 86 from the inflow surface 861 reaches the outflow surface 862 via this effective flow path. The particulate matter contained in the exhaust gas may adhere to the effective flow path of the partition wall 86 and be burned. Hereinafter, the porous partition wall 86 may be simply referred to as a porous body.

The method for specifying the effective or ineffective flow path according to the present disclosure is performed for the porous body which is the porous partition wall 86, and the effective or ineffective flow path contained in the porous body is specified. However, the method for identifying the effective or ineffective flow path according to the present disclosure is not limited to the porous body of the porous partition wall 86 of the segment 80 included in the ceramic filter 90 described above, and is incorporated into various other products or is used. Note that it is available for porous materials used in a variety of other applications. In some cases, the porous body is not a segment structure but a partition wall in an integrated honeycomb structure made of cordierite, Japanese Patent Application Laid-Open No. 2016-175045, Title of the invention: Sealed honeycomb structure, filing date: The entire contents of March 20, 2015 are incorporated herein by reference. The porous body subject to the method for specifying an effective or ineffective flow path according to the present disclosure is not limited to a filter, but is used for various applications such as a support substrate, a heat insulating material, a straightening vane, a selective transmission layer, and a heat exchange material. ..

The method for specifying an effective or ineffective flow path according to the present disclosure is performed based on structural data showing a three-dimensional structure of a porous body that should have an inflow surface and an outflow surface. Structural data showing the three-dimensional structure of the porous body can be obtained by various methods. It is recommended to use higher resolution structural data in order to elucidate the structure of the porous body with higher accuracy. From this point of view, the structural data showing the three-dimensional structure of the porous body is not necessarily limited to this, but is generated by the X-ray CT (Computed Tomography) apparatus 61. The structural data generated by the X-ray CT apparatus 61 is used by the computer 62 (see FIG. 4). Again, it is assumed that structural data showing the three-dimensional structure of the porous body is generated by a method other than the method using the X-ray CT apparatus.

FIG. 5 is a schematic perspective view of the porous body shown by the structural data acquired by the X-ray CT apparatus. FIG. 6 is a schematic view showing a schematic partial cross section of the porous body shown in FIG. 5, and the portion surrounded by the solid line shows the pores. As can be clearly seen from FIG. 6, there are pores having various cross-sectional shapes in the cross section of the porous body 10. The inventors of the present application predict that some pores are subspaces of an effective flow path for flowing a fluid from the inflow surface 10a to the outflow surface 10b of the porous body 10, but all the pores are not subspaces of the effective flow path. do. That is, it is expected that the pores include independent pores that are not spatially connected to the effective flow path. It is also expected to include pores, which are subspaces of the ineffective flow path where the fluid flows in partially or wholly but does not cause fluid flow. The effective flow path and the invalid flow path are distinguished from the viewpoint of whether or not the flow path contributes to the flow of the fluid from the inflow surface 10a to the outflow surface 10b. By selectively specifying the effective flow path contained in the porous body 10, the porous body 10 can be evaluated in a higher dimension or from another viewpoint. The evaluation result of the porous body 10 will be valuable information that will contribute to the development and manufacture of the porous body 10 in the future.

The X-ray CT apparatus 61 irradiates the porous body as a work with X-rays and observes the intensity of the X-rays transmitted through the porous body. The porous body, which is a work, rotates between the X-ray source and the X-ray detector. Alternatively, each of the X-ray source and the X-ray detector swirls around the outer circumference of the porous body. Reconstruction is performed based on an image showing the X-ray intensity distribution obtained by the X-ray detector, and structural data showing the three-dimensional structure of the porous body is generated. In some cases, the structural data is a three-dimensional set of voxels with voxel values (digital values) that indicate the absorptivity of X-rays. When the porous body consists only of a ceramic portion and pores, the voxel value of the voxel corresponding to the ceramic portion (hereinafter referred to as ceramic voxel) and the voxel value of the voxel corresponding to the pore (hereinafter referred to as pore boxel) are significantly different. The ceramic part is a part where a tangible material of a ceramic material is present. The pores are the parts where the gas is present. Various data formats and data structures of structural data can be considered and should not be limited to a specific type.

In addition to the ceramic portion and pores, the porous body may have residual carbon content (carbon) generated in the manufacturing process of the segment 80. Alternatively, the porous body may have carbon content derived from PM in the exhaust gas. Alternatively, the porous material may have carbon content in ash derived from fuel or engine oil. Alternatively, the porous body may have a catalyst supported by a segment 80, specifically, a partition wall 86, in addition to the ceramic portion and pores. It is assumed that these residual coals and catalysts have an X-ray absorption coefficient different from that of the ceramics portion and pores. Therefore, it is considered that the voxel values of the corresponding voxels have different values from the voxel values of ceramics or stomatal voxels. As the X-ray CT device 61, X-ray CT devices having various old and new device configurations can be adopted. For example, the X-ray CT apparatus 61 is a non-helical scan type or a helical scan type.

The computer 62 performs a fluid analysis on the porous body 10 based on the structural data showing the three-dimensional structure of the porous body 10 to have the inflow surface 10a and the outflow surface 10b, and at least the pressure of the fluid in the flow path contained in the porous body 10. Generate data showing the distribution. Fluid analysis is a simulation performed by a computer 62 solving an equation relating to the motion of a fluid. Various fluid analysis methods such as the difference method, the finite volume method, the finite element method, the particle method, and the lattice Boltzmann method can be adopted. When using a grid method such as the Lattice Boltzmann method, a computational grid (also called a grid or mesh) is set for the structural data. Although the particle method does not set a calculation grid, the pressure distribution can be calculated in the same manner as described later. The computer 62 sets grid points individually for each voxel. The grid point is located, for example, in the center of the voxel. The grid points set for voxels are, for example, indicated by xyz coordinates (see FIG. 5). It is not essential to provide individual grid points for all voxels included in the voxel set. In order to reduce the calculation cost borne by the computer 62, it is assumed that the number of lattice points less than the number of voxels is set. Alternatively, it is assumed that the number of lattice points larger than the number of voxels is set for more precise observation of the porous body 10. The partially enlarged view included in FIG. 5 schematically shows the grid spacing along the y-axis. The grid spacing along the x-axis = the grid spacing along the y-axis = the grid spacing along the z-axis is satisfied, but this is not always the case.

The fluid analysis itself such as the lattice Boltzmann method is performed by an application (software program) installed in the computer 62, and therefore, a detailed description of the specific method of the fluid analysis is omitted. As a result of fluid analysis such as the Lattice Boltzmann method, the flow velocity value, pressure value, and density are calculated for each grid point (if a grid point is set). A form in which one or more of the flow velocity value, the pressure value, and the fluid density are selectively calculated is also assumed.

The data showing the pressure distribution of the fluid obtained as a result of the fluid analysis is a set data of pressure values. When a computational grid is set, the data showing the pressure distribution of the fluid obtained as a result of the fluid analysis is a set of pressure values for each grid point. Since no fluid flows through the grid points corresponding to the ceramic voxels, the pressure values at those grid points are either no value, zero, or error values that occur during the fluid analysis process (eg, on the inflow surface). Obviously wrong value, such as the initial pressure value of the fluid). The grid points corresponding to the stomatal voxels, which are subspaces of the effective flow path, have a predetermined pressure value. The grid points corresponding to the stomatal voxels, which are subspaces of the invalid flow path, also have a predetermined pressure value. The grid points corresponding to the pore voxels where no fluid flows have a pressure value indicating zero or an error value. The error value can be easily removed using a threshold.

Subsequently, the computer 62 identifies an effective flow path for flowing the fluid from the inflow surface 10a to the outflow surface 10b based on the gradient of the pressure value generated along the flow direction of the fluid in the flow path of the porous body 10. When a fluid flows from the inflow surface 10a to the outflow surface 10b in an effective flow path, resistance is received from the wall surface defining the flow path, and the pressure value continuously decreases. The pressure value gradient can be identified by comparing the individual pressure values of two or more spatially adjacent grid points. Note that it is not limited to comparing the pressure values of adjacent grid points with one minimum grid spacing. A set of pressure values that change continuously along the flow direction of the fluid, or a set of grid points with such pressure values, corresponds to an effective flow path (or part thereof). On the other hand, a set of pressure values that do not change continuously along the flow direction of the fluid, or a set of lattice points having such pressure values, corresponds to an invalid flow path (or a part thereof). It should be noted that the flow direction of the fluid is not limited to the direction orthogonal to the inflow surface 861 and the outflow surface 862. A set of pressure values that do not change continuously along the flow direction of the fluid can be read as a set of constant pressure values that do not indicate the flow of the fluid.

FIG. 7 is a schematic diagram showing the results of fluid analysis performed on the simplified flow path. FIG. 8 is a graph showing changes in the pressure value on the isobaric surface shown in FIG. 7. In some cases, but not necessarily, the effective flow path is identified based on a plurality of isobaric surfaces having different pressure values along the flow direction of the fluid in the flow path. The plurality of isobaric surfaces are arranged according to the gradient of the pressure value generated along the flow direction of the fluid in the flow path. An isobaric surface is a surface with individual equal pressure values identified based on a pressure gradient by the processing of a fluid analysis application. For example, in an application, an isobaric surface is set based on the pressure value difference ΔP. The isobaric surface is a surface in which equal pressure values are distributed in a manner intersecting the fluid flow direction (X direction in FIG. 7). The isobaric surface can be a flat surface orthogonal to the flow direction of the fluid, or a partially or totally curved surface intersecting the flow direction of the fluid, but is not limited thereto.

The isobaric surface spacing is set based on the pressure value difference ΔP, so the distance between adjacent isobaric surfaces along the flow direction of the fluid in the flow path is the slope of the pressure value gradient of the fluid flowing in the flow path. It changes depending on. In a flow path where the gradient of the fluid pressure value is gentle, it is assumed that there are multiple lattice points between adjacent isobaric surfaces. On the other hand, depending on the application settings for the pressure value difference ΔP that determines the isobaric surface spacing and the gradient of the fluid pressure value, it is assumed that the distance between adjacent isobaric surfaces will be less than the grid spacing in the structural data. To.

In the case of FIGS. 7 and 8, the pressure value p1 of the isobaric surface s1> the pressure value p2 of the isobaric surface s2> the pressure value p3 of the isobaric surface s3> the pressure value p4 of the isobaric surface s4> the pressure value p5 of the isobaric surface s5> the isobaric surface. Pressure value p6 of s6> Pressure value p7 of isobaric surface s7> Pressure value p8 of isobaric surface s8> Pressure value p9 of isobaric surface s9> Pressure value p10 of isobaric surface s10> Pressure value p11 of isobaric surface s11> Isobaric surface s12 The pressure value p12> the pressure value p13 of the isobaric surface s13> the pressure value p14 of the isobaric surface s14 is satisfied. In addition, Δ _p1-p2 = Δ _p2-p3 = Δ _p3-p4 = Δ _p4-p5 = Δ _p5-p6 = Δ _p6-p7 = Δ _p7-p8 = Δ _p8- p9 = Δ p9 _-p10 = Δ _{p10- Satisfy p11} = Δ _p11-p12 = Δ _p12-p13 = Δ _p13-p14 .

The flow path 51 shown in FIG. 7 is an effective flow path specified based on a plurality of isobaric surfaces located according to the gradient of the pressure value generated along the flow direction of the fluid in the flow path. In the invalid flow path specified by the one-dot dashed circle C1, a plurality of isobaric surfaces are not arranged along the invalid flow path, unlike the effective flow path. Therefore, the invalid flow path specified by the one-dot dashed circle C1 is excluded.

The flow path 52 shown in FIG. 7 is an invalid flow path in which a fluid exists but no fluid flow occurs. The position and range of this invalid flow path can be specified based on the set of pressure values within a predetermined range. In short, it can be specified based on the set of pressure values belonging to the range of the pressure value difference ΔP that determines the spacing between the isobaric surfaces, which is shown by diagonal lines in FIG. 7. It is also assumed that this set of pressure values includes the portion of the effective flow path pointed to by the circle C2 of the alternate long and short dash line in FIG. 7. This error can be reduced by making the range of the pressure value difference ΔP that determines the spacing between the isobaric surfaces smaller and making the portion of the effective flow path pointed out by the circle C2 smaller (see FIG. 15). As an addition or alternative, the effective flow path can be specified based on the flow velocity pattern, and the overlapping portion of the invalid flow path and the effective flow path can be excluded.

FIG. 9 is a schematic schematic diagram mainly showing the flow path contained in the porous body. FIG. 10 is a reference diagram schematically showing the boundary between the effective flow path and the invalid flow path in the cross section VV of FIG. As can be seen from FIG. 9, a plurality of flow paths are formed in the porous body 10 so as to have a plurality of confluence points and a plurality of diversion points. FIG. 9 is a two-dimensional depiction of the flow path, but it is understood that the flow path is formed in a three-dimensional space. The first flow path 11 can be specified by the isobaric surfaces s1 to s6 as in FIGS. 7 and 8. The same applies to the second flow path 12 and the third flow path 13. The second flow path 12 branches into a sub flow path 121 and a sub flow path 122, the former merging into the first flow path 11 and the latter merging into the third flow path 13. The third flow path 13 branches into a sub flow path 131 and a sub flow path 132.

The flow path 21 spatially communicating with the first flow path 11 can be identified as an invalid flow path based on the same pressure value (or its range), as in FIGS. 7 and 8. The pores 22 located in the vicinity of the branch point of the third flow path 13 are independent pores through which the fluid does not flow, and the pressure value is 0, or the pressure value indicates an error value. The flow path 23 between the first flow path 11 and the sub flow path 131 is illustrated for reference. The flow path 23 is an effective flow path if there is a difference between the pressure value of the grid point located at the flow path end on the first flow path 11 side and the pressure value of the grid point located at the flow path end on the sub flow path 131 side. Become. The flow path 23 is an invalid flow path if there is no difference between the pressure value of the grid point located at the flow path end on the first flow path 11 side and the pressure value of the grid point located at the flow path end on the sub flow path 131 side. Become.

By identifying the effective flow path based on the isobaric surface, the identification of the effective flow path having continuity in the three-dimensional space is promoted, that is, the position, range, or distribution of the effective flow path in the three-dimensional space is frankly specified. Is promoted. When the effective flow path is specified based on the isobaric surface, the boundary s7 between the first flow path 11 and the flow path 21 is virtually determined between the isobaric surface s3 and the isobaric surface s4 as shown in FIGS. 9 and 10.

FIG. 11 is a schematic view showing a schematic partial cross section of the porous body shown in FIG. 5, and the solid line shows pores (hereinafter referred to as effective pores) which are subspaces of the newly specified effective flow path. , The dotted line indicates a pore (hereinafter referred to as an invalid pore) which is a subspace of the newly identified invalid flow path. According to the method according to the present disclosure described above, as can be seen from FIG. 11, an effective flow path can be specified, and an invalid flow path can be additionally or alternatively specified. As an addition or alternative to calculating the porosity in a cross section of the porous body 10 without distinguishing between effective and ineffective pores, the porosity of the effective or ineffective pores in the cross section of the porous body 10 can be calculated. .. It is expected that the new characteristics of the porous body 10 that could not be found by the porosity calculated without distinguishing between the effective pores and the ineffective pores will be elucidated.

FIG. 12 is a schematic flowchart of a method of identifying an effective flow path of the present disclosure. In step S1, structural data is generated. In step S2, data showing the pressure distribution is generated by fluid analysis based on the structural data. In step S3, the effective flow path is specified based on the gradient of the pressure value generated along the flow direction of the fluid in the flow path. As mentioned above, these steps are performed by one or more computers 62, but not necessarily.

The computer 62 performs fluid analysis on the porous body based on the structural data showing the three-dimensional structure of the porous body that should have an inflow surface and an outflow surface, and at least obtains data showing the pressure distribution of the fluid in the flow path contained in the porous body. It is a device that is generated and configured to identify an effective flow path for flowing fluid from the inflow surface to the outflow surface based on the gradient of the pressure value generated along the flow direction of the fluid in the flow path.

The computer 62 includes a CPU (central processing unit) and a storage unit, and the CPU executes a program stored in the storage unit. The storage unit is any one or a combination of two or more of a memory, a hard drive, a magnetic information recording medium, and an optical information recording medium. A storage unit is incorporated in the CPU, or both are connected via a communication bus. The computer 62 can have various other functional components such as a GPU (graphics processing unit), a network interface, and I / O.

It is also assumed that the above-mentioned device is composed of a plurality of computers. For example, some of the processing performed by the computer 62 is performed by a server connected via a network. In one embodiment, steps S2 and S3 are performed by a server connected via a network. In the grid method, the larger the number of grid points set in the structural data, the higher the calculation cost for the computer. From this point of view, it is assumed that the computational resources of other computers (servers) connected via the network will be used.

Again, invalid channels can be identified as an addition or alternative to identifying valid channels. The computer 62 is a flow surface from the inflow surface 10a based on a set of pressure values that do not change continuously along the flow direction of the fluid or a set of constant pressure values that do not indicate the flow of the fluid (or a range thereof). An invalid flow path that does not allow fluid to flow in 10b can be specified. As an alternative to a constant pressure value, a set of constant or within a predetermined range of pressure values can be used.

By specifying the invalid flow path, it becomes possible to calculate the porosity of the invalid flow path in a certain cross section of the porous body 10 and the volume of the invalid flow path in the porous body 10. It should be noted that, without distinguishing between the effective pores which are the partial spaces of the effective flow path and the invalid pores which are the partial spaces of the invalid flow path, it is based on the image analysis of the cross section of the porous body shown by the structural data generated by the X-ray CT apparatus. Therefore, the porosity of a certain cross section of the porous body 10 can be obtained. Further, the volume of the pores contained in the porous body 10 can be obtained by integrating the volumes of the pore voxels of the porous body shown by the structural data generated by the X-ray CT apparatus. Therefore, by subtracting the porosity of the invalid flow path in the cross section of the porous body 10 from the porosity of the cross section of the porous body 10 calculated based on the structural data generated by the X-ray CT apparatus, the porous body 10 is used. It is possible to calculate the porosity of the effective flow path in a certain cross section. The volume of the effective flow path of the porous body 10 can be calculated in the same manner.

FIG. 13 is a schematic flowchart of a method of identifying an invalid flow path of the present disclosure. In step S1, structural data is generated. In step S2, data showing the pressure distribution is generated by fluid analysis based on the structural data. In step S3, the invalid flow path is specified based on the set of pressure values within a predetermined range in the flow path. As mentioned above, these steps are performed by one or more computers 62, but not necessarily.

The computer 62 can determine the cross-sectional area of the effective flow path based on the isobaric surface. The isobaric surface may have a very complicated cross-sectional shape as can be seen from FIG. 11, but the computer 62 can calculate the area of the isobaric surface or an approximate value thereof by calculation by the application. The calculated area of the isobaric surface or its approximate value can be determined as the cross-sectional area of the effective flow path.

The computer 62 can calculate the volume of a part or the whole of the effective flow path specified as described above. The computer 62 can determine the volume of the effective flow path based on the isobaric surface. The partial volume of the effective flow path can be determined at least based on the distance between the first isobaric surface and the second isobaric surface in the flow direction of the fluid and the area of the first and / or second isobaric surface. By integrating the partial volume of the effective flow path, the volume of the effective flow path in a part or the whole of the porous body 10 can be calculated.

The computer 62 can determine the ratio of the total value of the individual cross-sectional areas of the effective flow path in the cross section of the porous body to the total value of the individual cross-sectional areas of the pores contained in the cross section of the porous body. The total value of the individual cross-sectional areas of the pores contained in a cross section of the porous body can be determined using structural data. For example, the total value of the individual cross-sectional areas of pores contained in a cross section of a porous body is obtained by binarizing the voxel value of ceramic voxels and the voxel value of pore voxels with one threshold value to calculate the area corresponding to the pore voxels. It is required by that. It is understood that binarizing the voxel value of ceramic voxels and the voxel value of pore voxels with a threshold value is useful in various calculation processes of the present disclosure.

The computer 62 can determine the ratio of the volume of the effective flow path to the total volume of pores contained in the porous body. The total volume of pores contained in the porous material can be determined based on the processing of structural data by the appropriate application, such as integrating the volume of pore voxels. The method for calculating the volume of the effective flow path is as described above.

The computer 62 can determine the ratio of the total cross-sectional area of the effective flow path included in the cross section of the porous body to the total cross-sectional area of both the pores and the ceramics portion in the cross section of the porous body. The total cross-sectional area of both the pores and the ceramic portion in a cross section of the porous body is, for example, the frame of the alternate long and short dash line shown in FIG. The total cross-sectional area of the effective flow path is determined as understood from the above disclosure.

The computer 62 can determine the ratio of the volume of the effective flow path to the volume of the porous body. The volume of the porous body is determined from the structural data or input to the computer as an initial value.

The computer 62 can determine the equivalent diameter of the isobaric surface based on the area of the isobaric surface and the perimeter. When the area of the isobaric surface is S, the perimeter is L, and the equivalent diameter is d, the equivalent diameter d is expressed by the following equation.
d = (4S / L)

As can be inferred from FIG. 6, the outer shape of the isobaric surface can take a complicated shape. This complex shape, however, can be replaced with one equivalent diameter based on the parameters of isobaric surface area and perimeter. The computer 62 can subsequently determine the distribution of equivalent diameters. Further, the computer 62 can determine the distribution of the number of isobaric surfaces having the same or equivalent diameter within the same range.

As described above, the data showing the pressure distribution of the fluid obtained as a result of the fluid analysis can also show the flow velocity distribution of the fluid flowing in the flow path. As described above, as a result of fluid analysis such as the lattice Boltzmann method, the flow velocity value, the pressure value, and the density are calculated for each lattice point (when the lattice point is set). The computer 62 determines the flow rate of the fluid passing through the isobaric surface in a unit time based on the area of the isobaric surface in which equal pressure values are distributed in the effective flow path intersecting the flow direction of the fluid and the flow velocity indicated by the data. Can be done. Further, the computer 62 can determine the flow rate flowing through a part or all of the effective flow paths contained in the porous body based on the sum of the flow rates determined for each isobaric surface.

The flow rate Q (m ³ / s) is calculated by multiplying the flow velocity v (m / s) and the cross-sectional area (m ² ).
Q = v × A

The computer 62 can determine the evaluation value regarding the filter characteristics for the isobaric surface based on the flow rate determined for the isobaric surface. Generally, the amount of gas flowing in a flow path having a large flow path diameter is large, and the amount of gas flowing in a flow path having a small flow path diameter is small. However, this relationship does not always hold in the porous body 10 in which the flow path is formed in a complicated manner. By determining the evaluation value based on the flow rate, it is possible to quantitatively evaluate how the flow path is used. For example, the evaluation value given to an isobaric surface having a large flow rate is low. The evaluation value given to the isobaric surface with a small flow rate is high. By obtaining the distribution of the evaluation values, the performance of the porous body in the filter application can be examined or evaluated.

[Example]
Structural data was generated by X-ray CT for the porous septa of the SiC segment for the ceramic filter. The porosity was calculated by computer image analysis for a cross section of the porous body shown in the structural data. Specifically, the ceramic part and the pores were distinguished by the binarization treatment. Next, the porosity of the pores in a certain cross section was determined by image analysis. This porosity does not distinguish between effective and ineffective pores. This treatment was continuously performed on a large number of cross sections in the direction from the inflow surface to the outflow surface of the porous body. M1 in FIG. 14 indicates the ratio of ineffective pores, M2 indicates the ratio of effective pores, and M3 indicates the ratio of the ceramic portion.

Based on the above structural data, the porous body shown by the structural data was subjected to fluid analysis by the lattice Boltzmann method, and the pressure value for each lattice point was calculated. Based on this pressure value gradient, the effective flow path was simply identified based on a plurality of isobaric surfaces arranged along the pressure value gradient. The porosity of the effective flow path was calculated by image analysis with a computer for the cross section of the porous body shown in the structural data. This treatment was performed on a large number of cross sections in the direction from the inflow surface to the outflow surface of the porous body. The black square in FIG. 14 shows the calculated change in the porosity of the effective pores. It can be said that the porosity of the effective pores is lower than expected.

Based on the above teachings, one of ordinary skill in the art can make various changes to each embodiment.

10 Porous body 10a Inflow surface 10b Outflow surface 61 X-ray CT device 62 Computer 80 Segment 90 Ceramics filter

Claims (20)

A fluid analysis is performed on the porous body based on the structural data showing the three-dimensional structure of the porous body having an inflow surface and an outflow surface, and at least data showing the pressure distribution of the fluid in the flow path contained in the porous body is generated. Process and
A method comprising the step of identifying an effective flow path for flowing the fluid from the inflow surface to the outflow surface based on a gradient of a pressure value generated along the flow direction of the fluid in the flow path. The method of claim 1, wherein the effective flow path is specified based on a plurality of isobaric surfaces having different pressure values along the flow direction of the fluid in the flow path. The method according to claim 2, wherein the cross-sectional area of the effective flow path is determined based on the isobaric surface. The method according to claim 2 or 3, wherein the volume of the effective flow path is determined based on the isobaric surface. The partial volume of the effective flow path is determined at least based on the separation distance between the first isobaric surface and the second isobaric surface in the flow direction of the fluid and the area of the first and / or second isobaric surface. The method according to any one of claims 2 to 4. The claim further comprises a step of determining the ratio of the total value of the individual cross-sectional areas of the effective flow path in the cross section of the porous body to the total value of the individual cross-sectional areas of the pores contained in the cross section of the porous body. The method according to any one of 1 to 5. The method according to any one of claims 1 to 6, further comprising a step of determining the ratio of the volume of the effective flow path to the total volume of pores contained in the porous body. A claim further comprising determining the ratio of the total cross-sectional area of the effective flow path contained in the cross section of the porous body to the total cross-sectional area of both the pores and the ceramics portion in a cross section of the porous body. Item 2. The method according to any one of Items 1 to 7. The method according to any one of claims 1 to 8, further comprising a step of determining the ratio of the volume of the effective flow path to the volume of the porous body. The method according to claim 2, further comprising a step of determining an equivalent diameter of the isobaric surface based on the area of the isobaric surface and the peripheral length. 10. The method of claim 10, further comprising the step of determining the distribution of equivalent diameters. 10. The method of claim 10 or 11, further comprising determining the distribution of the number of isobaric surfaces of equivalent diameter within the same or range. The data also show the flow velocity distribution of the fluid flowing through the flow path.
The flow rate of the fluid passing through the isobaric surface in a unit time is determined based on the area of the isobaric surface in which equal pressure values are distributed in the effective flow path intersecting the flow direction of the fluid and the flow velocity indicated by the data. The method according to any one of claims 1 to 12, further comprising a step. 13. The method of claim 13, further comprising determining the flow rate flowing through some or all of the effective flow paths contained in the porous body based on the sum of the flow rates determined for each isobaric surface. 13. The method of claim 13 or 14, further comprising determining an evaluation value for filter characteristics for the isobaric surface based on the flow rate determined for the isobaric surface. The method according to any one of claims 1 to 15, wherein the structural data is a three-dimensional set of voxels having digital values. Further including a step of setting grid points for the structural data,
13. the method of. A fluid analysis is performed on the porous body based on the structural data showing the three-dimensional structure of the porous body that should have an inflow surface and an outflow surface, and at least data showing the pressure distribution of the fluid in the flow path contained in the porous body is generated. ,
A device configured to identify an effective flow path for flowing the fluid from the inflow surface to the outflow surface based on the gradient of the pressure value generated along the flow direction of the fluid in the flow path. A fluid analysis is performed on the porous body based on the structural data showing the three-dimensional structure of the porous body having an inflow surface and an outflow surface, and at least data showing the pressure distribution of the fluid in the flow path contained in the porous body is generated. Process and
A method comprising the step of identifying an ineffective flow path that does not allow the fluid to flow from the inflow surface to the outflow surface based on a set of pressure values within a predetermined range that does not indicate the flow of the fluid in the flow path. A fluid analysis is performed on the porous body based on the structural data showing the three-dimensional structure of the porous body that should have an inflow surface and an outflow surface, and at least data showing the pressure distribution of the fluid in the flow path contained in the porous body is generated. ,
An apparatus configured to identify an ineffective flow path that does not allow the fluid to flow from the inflow surface to the outflow surface, based on a set of pressure values within a predetermined range that does not indicate the flow of the fluid in the flow path.

Images